Direct Imaging of Lipid-Ion Network Formation under Physiological Conditions by Frequency Modulation Atomic Force Microscopy

Fukuma, Takeshi; Higgins, Michael J.; Jarvis, Suzanne P.

doi:10.1103/physrevlett.98.106101

Cited by 160 publications

(157 citation statements)

References 30 publications

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“…The above findings are in good agreement with experimental data [6][7][8][9] and with previously reported computational results. 6,12,15 It is, however, very instructive to consider the sensitivity of the results to a force-field employed for modeling salt ions.…”

Section: Resultssupporting

confidence: 93%

Effect of NaCl and KCl on Phosphatidylcholine and Phosphatidylethanolamine Lipid Membranes: Insight from Atomic-Scale Simulations for Understanding Salt-Induced Effects in the Plasma Membrane

Gurtovenko

Vattulainen²

2008

J. Phys. Chem. B

225

250

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To gain a better understanding of how monovalent salt under physiological conditions affects plasma membranes, we have performed 200 ns atomic-scale molecular dynamics simulations of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) lipid bilayers. These two systems provide representative models for the outer and inner leaflets of the plasma membrane, respectively. The implications of cation-lipid interactions in these lipid systems have been considered in two different aqueous salt solutions, namely NaCl and KCl, and the sensitivity of the results on the details of interactions used for ions is determined by repeating the simulations with two distinctly different force fields. We demonstrate that the main effect of monovalent salt on a phospholipid membrane is determined by cations binding to the carbonyl region of a membrane, while chloride anions mostly stay in the water phase. It turns out that the strength and character of the cation-lipid interactions are quite different for different types of lipids and cations. PC membranes and Na + ions demonstrate strongest interactions, leading to notable membrane compression. This finding was confirmed by both force fields (Gromacs and Charmm) employed for the ions. The binding of potassium ions to PC membranes (and the overall effect of KCl), in turn, was found to be much weaker mainly due to the larger size of a K + ion compared to Na + . Furthermore, the effect of KCl on PC membranes was found to be force-field sensitive: The binding of a potassium ion was not observed at all in simulations performed with the Gromacs forcefield, which seems to exaggerate the size of a K + ion. As far as PE lipid bilayers are concerned, they are found to be influenced by monovalent salt to a significantly lesser extent compared to PC bilayers, which is a direct consequence of the ability of PE lipids to form both intra-and intermolecular hydrogen bonds and hence to adopt a more densely packed bilayer structure. Whereas for NaCl we observed weak binding of Na + cations to the PE lipid-water interface, in the case of KCl we witnessed almost complete lack of cation binding. Overall, our findings indicate that monovalent salt ions affect lipids in the inner and outer leaflets of plasma cell membranes in substantially different ways.

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Section: Resultssupporting

confidence: 93%

Effect of NaCl and KCl on Phosphatidylcholine and Phosphatidylethanolamine Lipid Membranes: Insight from Atomic-Scale Simulations for Understanding Salt-Induced Effects in the Plasma Membrane

Gurtovenko

Vattulainen²

2008

J. Phys. Chem. B

225

250

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“…However, specialized instruments were used and the nature of the tip-sample interaction remains an issue of debate. Dynamic AFM has the ability to probe the solid-liquid interface [18][19][20][21] , but an interpretation of experimental results remains difficult 22,23 . Traditionally, interfaces are characterized by an interfacial energy, IE, the sum of the two surface energies in vacuum minus the work of adhesion (W SL ) necessary to separate the surfaces (Dupré Equation 24 ).…”

Section: Use Policymentioning

confidence: 99%

“…These forces are generally of relatively short range and strongly dependent on the local nature of the solid, thus limiting the interfacial liquid to extend only a few molecular diameters away from the surface 6,22,26 . AFM has allowed direct probing of the density variations at the interfacial layer as a function of distance from the interface for confined liquid layers at the surface of both hard 20 and biological materials 21 . However, to date, experimental measurements of IE rely on averaging over large areas 6,26,27 , precluding investigations of lateral variations, mainly at the nanoscale.…”

mentioning

confidence: 99%

Direct mapping of the solid–liquid adhesion energy with subnanometre resolution

et al. 2010

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Atomic force microscopy's 7 (AFM) ability of visualizing the topography and the property of surfaces and interfaces at a molecular level 8 has enabled a rapid development in the understanding of surface phenomena. Its versatility allows the exploration of hard and soft materials in vacuum 9-12 , in air 13 , but also in complex liquids 14,15 , often allowing imaging at sub-nanometre and sometimes atomic resolution 16 . In dynamic mode 17 (vibrating cantilever), AFM has proven sensitive to the interfacial compliance of viscous liquids and provided quantitative information about the structure of liquid layers between the AFM tip and the solid surface 18 , with, in some cases, atomic resolution 15 . However, specialized instruments were used and the nature of the tip-sample interaction remains an issue of debate. Dynamic AFM has the ability to probe the solid-liquid interface [18][19][20][21] , but an interpretation of experimental results remains difficult 22,23 . Traditionally, interfaces are characterized by an interfacial energy, IE, the sum of the two surface energies in vacuum minus the work of adhesion (W SL ) necessary to separate the surfaces (Dupré Equation 24 ). The latter is de facto the energy spent to restructure the interface due to the atomistic interaction between the two materials (Fig. 1c). In practice at a solid-liquid interface this is the energy that generates density variations and structuring of the liquid close to the interface. Hereafter we will call this layer of liquid which differs from the bulk

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“…19 Recently developments in the field of AFM have made it possible to achieve sub-nanometer mapping of soft and hard surfaces in solution paving the way for in-situ local observations of a functional DSC's surface. [20][21][22] Here we report in situ molecular-level AFM images of adsorbed dye molecules at mesoporous and flat TiO 2 surfaces in a device-relevant liquid. We used the amphiphilic ruthenium complex Z907 (diphenyl-nonyl diphenyl-carboxyl dithio octaruthenium) dye (insert in Figure 2) due to its wide-spread use in DSCs, its good performance in long-term stability tests, and the fact that it is less prone to aggregation than other dyes.…”

Section: Introductionmentioning

confidence: 96%

In Situ Mapping of the Molecular Arrangement of Amphiphilic Dye Molecules at the TiO₂ Surface of Dye-Sensitized Solar Cells

Voïtchovsky

Astani

Tavernelli

et al. 2015

ACS Appl. Mater. Interfaces

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Citation for published item:o¤ %t hovskyD uF nd esh ri est niD xF nd vernelliD sF nd etre ultD xF nd othlis ergerD F nd tell iD pF nd qr¤ tzelD wF nd erne r rmsD rF @PHISA 9snEsitu m pping of the mole ul r rr ngement of mphiphili dye mole ules t the iyP surf e of dye sensitized sol r ellsF9D eg pplied m teri ls interf esFD U @PHAF ppF IHVQREIHVRPF Further information on publisher's website: httpXGGdxFdoiForgGIHFIHPIG s miFS HITQV Publisher's copyright statement: This document is the Accepted Manuscript version of a Published Work that appeared in nal form in ACS applied materials interfaces, copyright c 2015 American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/acsami.5b01638. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Just Accepted "Just Accepted" manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides "Just Accepted" as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. "Just Accepted" manuscripts appear in full in PDF format accompanied by an HTML abstract. "Just Accepted" manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). "Just Accepted" is an optional service offered to authors. Therefore, the "Just Accepted" Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the "Just Accepted" Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these "Just Accepted" manuscripts. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

show abstract

Direct Imaging of Lipid-Ion Network Formation under Physiological Conditions by Frequency Modulation Atomic Force Microscopy

Cited by 160 publications

References 30 publications

Effect of NaCl and KCl on Phosphatidylcholine and Phosphatidylethanolamine Lipid Membranes: Insight from Atomic-Scale Simulations for Understanding Salt-Induced Effects in the Plasma Membrane

Effect of NaCl and KCl on Phosphatidylcholine and Phosphatidylethanolamine Lipid Membranes: Insight from Atomic-Scale Simulations for Understanding Salt-Induced Effects in the Plasma Membrane

Direct mapping of the solid–liquid adhesion energy with subnanometre resolution

In Situ Mapping of the Molecular Arrangement of Amphiphilic Dye Molecules at the TiO₂ Surface of Dye-Sensitized Solar Cells

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Direct Imaging of Lipid-Ion Network Formation under Physiological Conditions by Frequency Modulation Atomic Force Microscopy

Cited by 160 publications

References 30 publications

Effect of NaCl and KCl on Phosphatidylcholine and Phosphatidylethanolamine Lipid Membranes: Insight from Atomic-Scale Simulations for Understanding Salt-Induced Effects in the Plasma Membrane

Effect of NaCl and KCl on Phosphatidylcholine and Phosphatidylethanolamine Lipid Membranes: Insight from Atomic-Scale Simulations for Understanding Salt-Induced Effects in the Plasma Membrane

Direct mapping of the solid–liquid adhesion energy with subnanometre resolution

In Situ Mapping of the Molecular Arrangement of Amphiphilic Dye Molecules at the TiO2 Surface of Dye-Sensitized Solar Cells

Contact Info

Product

Resources

About

In Situ Mapping of the Molecular Arrangement of Amphiphilic Dye Molecules at the TiO₂ Surface of Dye-Sensitized Solar Cells